H ion-pumping across the mitochondrial membrane is an integral part of the overall process of oxidative phosphorylation in mitochondria. There is evidence for two types of H ion-pumps in this system: one associated with electron transport, which generates a H ion-gradient, and one associated with the utilization of the gradient energy for ATP synthesis. The principal aim of the project is to study the detailed mechanism of H ion-translocation associated with the latter system. H ion-translocation mediated by the mitochondrial DCCD-binding proteolipid will be studied as well as its regulation by other hydrophoic membrane proteins, such as the oligomycin sensitivty conferring protein (or OSCP), F6, coupling factor B and the uncoupler binding protein. One method to be used would utilize incorporation of the proteins into K ion-loaded liposomes for measurement of passive H ion-uptake initiated by valinomycin. In the second method, the proteins will be incorporated into planar bilayer membranes for measurement of electrical parameters.